C++ (Cpp) BTC_PUBKEY::SetPublicElement Examples

Example #1

File: EncryptionUtils.cpp Project: CarltonCode/BitcoinArmory

/////////////////////////////////////////////////////////////////////////////
// Deterministically generate new public key using a chaincode
SecureBinaryData CryptoECDSA::ComputeChainedPublicKey(
                                SecureBinaryData const & binPubKey,
                                SecureBinaryData const & chainCode,
                                SecureBinaryData* multiplierOut)
{
   if(CRYPTO_DEBUG)
   {
      cout << "ComputeChainedPUBLICKey:" << endl;
      cout << "   BinPub: " << binPubKey.toHexStr() << endl;
      cout << "   BinChn: " << chainCode.toHexStr() << endl;
   }
   static SecureBinaryData SECP256K1_ORDER_BE = SecureBinaryData::CreateFromHex(
           "fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141");

   // Added extra entropy to chaincode by xor'ing with hash256 of pubkey
   BinaryData chainMod  = binPubKey.getHash256();
   BinaryData chainOrig = chainCode.getRawCopy();
   BinaryData chainXor(32);
      
   for(uint8_t i=0; i<8; i++)
   {
      uint8_t offset = 4*i;
      *(uint32_t*)(chainXor.getPtr()+offset) =
                           *(uint32_t*)( chainMod.getPtr()+offset) ^ 
                           *(uint32_t*)(chainOrig.getPtr()+offset);
   }

   // Parse the chaincode as a big-endian integer
   CryptoPP::Integer mult;
   mult.Decode(chainXor.getPtr(), chainXor.getSize(), UNSIGNED);

   // "new" init as "old", to make sure it's initialized on the correct curve
   BTC_PUBKEY oldPubKey = ParsePublicKey(binPubKey); 
   BTC_PUBKEY newPubKey = ParsePublicKey(binPubKey);

   // Let Crypto++ do the EC math for us, serialize the new public key
   newPubKey.SetPublicElement( oldPubKey.ExponentiatePublicElement(mult) );

   if(multiplierOut != NULL)
      (*multiplierOut) = SecureBinaryData(chainXor);

   //LOGINFO << "Computed new chained public key using:";
   //LOGINFO << "   Public key: " << binPubKey.toHexStr().c_str();
   //LOGINFO << "   PubKeyHash: " << chainMod.toHexStr().c_str();
   //LOGINFO << "   Chaincode:  " << chainOrig.toHexStr().c_str();
   //LOGINFO << "   Multiplier: " << chainXor.toHexStr().c_str();

   return CryptoECDSA::SerializePublicKey(newPubKey);
}